Identification of the cAMP-Responsive Enhancer of the Murine ABCA1 Gene. Requirement for CREB1 and STAT3/4 Elements

Authors:
Le Goff W, Zheng P, Brubaker G and Smith JD
In:
Source: Arterioscler Thromb Vasc Biol
Publication Date: (2006)
Issue: 26(3): 527-33
Research Area:
Cardiovascular
Cells used in publication:
RAW 264.7
Species: mouse
Tissue Origin: blood
Platform:
Nucleofectorâ„¢ I/II/2b
Abstract
OBJECTIVE: To determine the mechanism by which expression of the murine ABCA1 gene is highly induced by cAMP analogues. METHODS AND RESULTS: ABCA1 mRNA turnover cannot account for its induction by cAMP. Thus cAMP induction of ABCA1 mRNA occurs at a transcriptional level. Shotgun cloning DNA fragments from the murine ABCA1 locus identified a strong cAMP responsive enhancer located in the first intron, which led to 25- to 100-fold cAMP-mediated induction of reporter gene activity. Deletions and mutations of this enhancer led to the identification a cAMP-responsive element (CRE) that was essential for the cAMP induction. Furthermore, the capacity of this CRE site to mediate the cAMP induction required the presence of a STAT3/4 element located 81 bp away. A dominant-negative CREB expression vector inhibited the cAMP induction of ABCA1, demonstrating that CREB was required for cAMP induction of ABCA1 expression in RAW264.7 cells. CONCLUSIONS: Phospho-CREB1 controls the cAMP-mediated induction of murine ABCA1 gene expression through a CRE site acting in cooperation with a nearby STAT element. This CRE site is not conserved in the human ABCA1 gene, explaining why human ABCA1 is not strongly stimulated by cAMP analogs.